This application requests funds for upgrading the electron microscope facility at the La Jolla Cancer Research Foundation. With the growth of the Foundation, this facility has become an increasingly important resource for a variety of research projects. The techniques of rotary shadowing and immunogold labelling are being used extensively for studies of the extracellular matrix, cell surface, and cytoskeleton. Currently, the electron microscope facility is equipped with an Hitachi H-600-2 scanning and transmission electron microscope, an ultramicrotome, a critical point dryer with sputter coater and an evaporator for rotary shadowing. The level of sophistication of the facility in both experimental design and data analysis could be substantially improved through the acquisition of (1) instrumentation for image processing and (2) equipment for ultracryomicrotomy. Computerized image analysis would markedly enhance the capacity to characterize the dimensions and structural features of rotary shadowed molecules and immunogold-labelled specimens, processes that are presently done by hand from photographs. Because it is capable of superimposing and averaging multiple images and of recognizing periodicity and patterns of clustering, the image processing system greatly expands the possible data base and at the same time reduces errors of interpretation. Use of the ultracryomicrotome permits the preparation of ultrathin frozen sections in which neither the cellular ultrastructure nor the reactivity of antigenic epitopes is compromised by fixation and embedding. These are crucial requirements for high resolution analysis of immunogold-labelled preparations.